奖励驱动的双任务加工过程中的分离脑机制：来自ERP的证据

运用事件相关电位技术, 采用分支双任务范式, 探讨在奖励驱动的双任务加工过程中, 第一任务奖励编码和第二任务奖励编码的时间进程及其脑机制。结果发现：双任务的反应时显著大于单任务的反应时; 单任务的N2波幅显著大于双任务条件; 双任务的P3波幅显著大于单任务条件。双任务加工过程中奖励编码的半球效应主要体现在P3上, 且右半球参与第一任务奖励信息的编码, 驱动第一任务; 两半球协同参与第二任务奖励信息的编码, 驱动第二任务。结果表明：双任务所耗费的心理资源更多, 同时双任务加工过程中第一任务奖励信息编码的半球优势效应与任务的性质有关。     

Control of stimulus-response translation in dual-task performance

In contradiction to stimulus-response- (S-R-) translation bottleneck models of dual-task control, stimulus processing in a primary task is affected by its compatibility with the response in a secondary, later performed task (Hommel, 1998a)- an indication of parallel S-R translation. Here we show that this backward-compatibility effect is independent of working-memory load, whether this is induced by an extra memory task (Experiment 1) or by increasing the number of S-R alternatives in the primary task (Experiment 2). However, backward effects occur even when the secondary task is no longer carried out (Experiment 3) and they are strongly affected by the inconsistency of previously used S-R mappings (Experiment 4). These findings suggest that S-R translation is (or can be) capacity-independent and automatic even under multiple-task conditions, and that it is mediated by direct S-R associations that emerge after only little practice.     

Improved intertask coordination after extensive dual-task practice

This study examines whether an improved intertask coordination skill is acquired during extensive dual-task training and whether it can be transferred to a new dual-task situation. Participants practised a visual–manual task and an auditory–vocal task. These tasks were trained in two groups matched in dual-task performance measures before practice: a single-task practice group and a hybrid practice group (including single-task and dual-task practice). After practice, the single-task practice group was transferred to the same dual-task situation as that for the hybrid practice group (Experiment 1), both groups were transferred to a dual-task situation with a new visual task (Experiment 2), and both groups were transferred to a dual-task situation with a new auditory task matched in task difficulty (Experiment 3). The results show a dual-task performance advantage in the hybrid practice group over the single-task practice group in the practised dual-task situation (Experiment 1), the manipulated visual-task situation (Experiment 2), and the manipulated auditory-task situation (Experiment 3). In all experiments, the dual-task performance advantage was consistently found for the auditory task only. These findings suggest that extended dual-task practice improves the skill to coordinate two tasks, which may be defined as an accelerated switching operation between both tasks. This skill is relatively robust against changes of the component visual and auditory tasks. We discuss how the finding of task coordination could be integrated in present models of dual-task research.     

Improved intertask coordination after extensive dual-task practice

This study examines whether an improved intertask coordination skill is acquired during extensive dual-task training and whether it can be transferred to a new dual-task situation. Participants practised a visual-manual task and an auditory-vocal task. These tasks were trained in two groups matched in dual-task performance measures before practice: a single-task practice group and a hybrid practice group (including single-task and dual-task practice). After practice, the single-task practice group was transferred to the same dual-task situation as that for the hybrid practice group (Experiment 1), both groups were transferred to a dual-task situation with a new visual task (Experiment 2), and both groups were transferred to a dual-task situation with a new auditory task matched in task difficulty (Experiment 3). The results show a dual-task performance advantage in the hybrid practice group over the single-task practice group in the practised dual-task situation (Experiment 1), the manipulated visual-task situation (Experiment 2), and the manipulated auditory-task situation (Experiment 3). In all experiments, the dual-task performance advantage was consistently found for the auditory task only. These findings suggest that extended dual-task practice improves the skill to coordinate two tasks, which may be defined as an accelerated switching operation between both tasks. This skill is relatively robust against changes of the component visual and auditory tasks. We discuss how the finding of task coordination could be integrated in present models of dual-task research.     

A methodological assessment and evaluation of dual-task paradigms

This article outlines three major assumptions often implicitly made in dual-task experiments conducted to assess attentional capacity requirements of memorial processes. These assumptions are shown to be incorrect. Three criteria which should be met in dual-task experiments that draw inferences from secondary task decrements are proposed: (1) there should be resource trade-off with the secondary task sensitive to the resource demands of the primary task; (2) there should be equivalence of single and dual primary task performance; and (3) the secondary task must remain resource sensitive throughout the experiment. An experiment was carried out in which the primary and secondary tasks were designed according to these criteria. The results demonstrate that when the criteria are met then secondary task performance can be predictive of primary task difficulty: however, the experiment also highlights the fact that a simple assessment of capacity will not predict total task performance.     

Task-set inertia and memory-consolidation bottleneck in dual tasks

Three dual-task experiments examined the influence of processing a briefly presented visual object for deferred verbal report on performance in an unrelated auditory-manual reaction time (RT) task. RT was increased at short stimulus-onset asynchronies (SOAs) relative to long SOAs, showing that memory consolidation processes can produce a functional processing bottleneck in dual-task performance. In addition, the experiments manipulated the spatial compatibility of the orientation of the visual object and the side of the speeded manual response. This cross-task compatibility produced relative RT benefits only when the instruction for the visual task emphasized overlap at the level of response codes across the task sets (Experiment 1). However, once the effective task set was in place, it continued to produce cross-task compatibility effects even in single-task situations (“ignore” trials in Experiment 2) and when instructions for the visual task did not explicitly require spatial coding of object orientation (Experiment 3). Taken together, the data suggest a considerable degree of task-set inertia in dual-task performance, which is also reinforced by finding costs of switching task sequences (e.g., AC → BC vs. BC → BC) in Experiment 3.     

Mental effort and task interference in auditory attention

Dual-task performance was examined in three experiments. The primary task was to repeat or to add one to four digits presented auditorily at a rate of 1 digit/second. This primary task was combined with three different secondary tasks in which subjects listened to a list of words either for later recognition of some of the words (Experiment 1) or for detection and a later report of a target word (Experiments 2 and 3). Different patterns of task interference were obtained. Recognition performance was sensitive to between-task variations in capacity demands but did not reflect momentary attentional demands within the primary task. Detection performance reflected both between-task and within-task variation in capacity demands of the primary task. The interference between the primary and the secondary task was mutual, with more interference when the selection-cue in the detection task was a category name than when it was the target word itself. These findings are discussed in terms of effort theory of attention and the role of attentional strategies in dual-task performance.     

The cost of a strategy

Abstract

Experiment 1 demonstrated a new kind of dual-task interference effect. The primary task was a speeded left-right discrimination of stimulus position (R1). The un speeded secondary task consisted of reporting verbally whether the stimuli were the same or different (R2). Stimulus exposure time was either 150 or 2000 msec. Two groups of subjects performed the primary task only, whereas two other groups performed both tasks and were instructed to emit R1 before R2. It was reasoned that the decision would be made to emit R1 before R2, and that this decision would produce a lengthening of R1. The results supported this prediction. Experiment 2 showed that the interference effect also occurred when the subjects were not explicitly instructed to emit R1 before R2, and was not due to either the mere presence of the second task or to response grouping. Experiments 3 and 4 compared two possible models for explaining the interference effect, i.e. the capacity-sharing model and the postponement model. As predicted by the postponement model, task difficulty did not interact, or interacted underadditively, with task overlap (Experiment 3), and the interference effect was not influenced by the amount of processing resources devoted to the primary task (Experiment 4). It was concluded that this new type of interference effect is best explained by the version of the postponement model that locates the bottleneck at the decision stage.     

Practice-related reduction of dual-task costs under conditions of a manual-pedal response combination

Severe dual-task costs emerge when two tasks are performed at the same time. Schumacher, Seymour, Glass, Kieras, and Meyer (2001) showed a complete reduction of dual-task costs after extensive dual-task practice with a visual-manual (VM) task and an auditory-verbal (AV) task. First, we replicated these findings and found task conditions sufficient to achieve a high level of dual-task cost reduction (Experiment 1). Using these conditions, we tested whether the Schumacher et al. findings generalise to a different dual-task situation, in which participants practised a VM task and an auditory-pedal (AP) task (VM-AP) conjointly (Experiment 2). In the VM-AP task situation we found reduced dual-task costs after practice. Dual-task costs, however, remained on a high level after eight sessions of practice and also when extending practice to 12 sessions. No single participant showed evidence for time sharing in the VM-AP dual task. These results suggest that the finding of complete dual-task cost reduction does not generalise to the VM-AP task combination used in the present study. We discuss different factors potentially relevant for the observation of persisting dual-task costs over practice in the VM-AP task.     

Additional effects of a cognitive task on dual-task training to reduce dual-task interference

ObjectiveWhen we perform dual-tasks in daily life, task performance is generally reduced. As these reductions in performance (i.e., dual-task interference) are responsible for various accidents such as falls, the repeated practice of dual-task (i.e., dual-task training) is often implemented to reduce dual-task interference. However, the risk of various accidents increases with longer dual-task training, as dual-task interference cannot be avoided. Therefore, it is important to achieve training goals more rapidly during dual-task training. This study sought to determine whether a combination of dual-task training and cognitive tasks would accelerate training effects.DesignThe experimental design included four groups: 1) cognitive task training group, 2) dual-task training group, 3) cognitive task and dual-task training group, and 4) non training group.MethodWe assessed single- and dual-task performance before and after the 2-week training sessions. We adopted a dual-task involving knee extension and an auditory reaction, and used N-back task as a cognitive task. On the other hand, dual-task training was the same method to assess dual-task performance.ResultDual-task interference was reduced in all groups in both the tasks. However, the number of participants in the cognitive task and dual-task training group who achieved a reduction in dual-task cost was significantly higher than those in other groups.ConclusionThese findings could contribute to the development of an effective method for reducing dual-task interference and resolving issues caused by dual-task interference in daily life.     

Individuals lower in working memory capacity are particularly vulnerable to anxiety's disruptive effect on performance

Abstract

Anxiety has a disruptive effect on performance in a number of domains. The purpose of this study was to determine whether individual differences in working memory (WM) capacity are related to an individual's susceptibility to anxiety's detrimental effect on performance. Fifty undergraduate students (28 females) were administered the State-Trait Anxiety Inventory (STAI) (Spielberger, Gorsuch, Lushene, Vagg, & Jacobs, 1983) to measure trait anxiety and the automated operation span task to measure WM capacity (Unsworth, Heitz, Schrock, & Engle, 2005). Then, they performed a highly demanding dual-task that consisted of a primary short-term memory task and a secondary tone-discrimination task that served as a measure of spare capacity. Anxiety and WM capacity interacted to affect performance on the auditory task so that those low in WM capacity were particularly vulnerable to anxiety's disruptive effect, whereas those high in WM capacity were buffered against anxiety's effect. These findings suggest that WM capacity may be an important factor in determining which individuals underperform on anxiety-provoking tests such as scholastic achievement tests.     

Age-related Differences in Working Memory and Force Control under Dual-task Conditions

ABSTRACT

The aim of this study was to investigate the relationship between force control and cognitive performance under dual-task conditions in younger (18–22 years) and older adults (65–77 years). Cognitive (n-back test) and motor performance (force-tracking) was measured independently and simultaneously. Results indicated overall age-related differences for the n-back and the force-tracking task. Age-related differences increased during dual-task conditions. While younger adults exhibited no decrease in cognitive or motor performance during dual-task conditions, older adults showed a decrease in motor and cognitive performance. Additionally, when older adults made an error in the cognitive task they tended to show greater variability in the force-tracking task. These results suggest that cognitive motor deficits are responsible for older adults' performance decrements under dual-task conditions.     

Mood states determine the degree of task shielding in dual-task performance

Current models of multitasking assume that dual-task performance and the degree of multitasking are affected by cognitive control strategies. In particular, cognitive control is assumed to regulate the amount of shielding of the prioritised task from crosstalk from the secondary task. We investigated whether and how task shielding is influenced by mood states. Participants were exposed to two short film clips, one inducing high and one inducing low arousal, of either negative or positive content. Negative mood led to stronger shielding of the prioritised task (i.e., less crosstalk) than positive mood, irrespective of arousal. These findings support the assumption that emotional states determine the parameters of cognitive control and play an important role in regulating dual-task performance.     

An internal focus of attention is optimal when congruent with afferent proprioceptive task information

Whilst benefits of an external focus are shown to govern several characteristics of skill execution, specificity theory indicates that sources of afferent information most useful to performance execution are typically prioritised during processing.ObjectivesWe investigated whether an internal focus facilitates performance when pertinent afferent information is proprioceptive in nature and congruent with attentional focus. We also considered whether the mechanisms behind attentional focus differences are attributable to planning processes or online motor control.DesignExperiments 1 and 2 adopted a randomised design, whilst experiment 3 used a repeated measures approach.MethodIn Experiment 1 we investigated movement variability as a measure of planning and error correction under external and internal focus conditions in an aiming task. Experiment 2 removed visual information to increase pertinence of proprioceptive feedback for movement execution and Experiment 3 adopted a leg-extension task, where proprioceptive salience was enhanced using an ankle weight. We hypothesised that this would increase congruency between internal focus instructions and movement production.ResultsExperiments 1 and 2 revealed reduced amplitude errors under an internal focus whilst Experiment 3 showed similar findings with the addition of lower EMG activity when adopting an internal focus. Movement variability findings were indicative of enhanced planning.ConclusionsWhen pertinence of proprioceptive information was amplified, benefits of an internal focus were more pronounced and performance was higher. Participants were better able to focus on movement characteristics to process proprioceptive feedback: something not afforded under an external focus. This raises doubts regarding the rigidity of the constrained action hypothesis.     

Attentional resource demands of visual word recognition in naming and lexical decisions.

Attentional demands of lexical access were assessed with dual-task methodology. Subjects performed an auditory probe task alone (single-task) or combined (dual-task) with either a lexical decision or a naming task. In Experiment 1, probe performance showed a decrement from single- to dual-task conditions during recognition of words in both lexical decision and naming tasks. In addition, decrements in probe performance were larger during processing of low-frequency compared with high-frequency words in both of the word recognition tasks. Experiment 2 showed that the time course of frequency-sensitive demands was similar across lexical decision and naming tasks and that attention is required early in the word recognition sequence. The results support the assumption that lexical access is both frequency sensitive and attention demanding.     

Constraints on using the dual-task methodology to specify the degree of central executive involvement in cognitive tasks

The dual-task paradigm has been used to examine the role of the central executive in various cognitive tasks. In these studies, performance decrements in primary cognitive tasks performed concurrently with secondary executive tasks have been interpreted as evidence for the involvement of the central executive in those primary tasks. In the present study, we examined the effects of different secondary tasks on performance of three psychometric visuospatial tasks. The decrement in performance of these tasks when they were paired with secondary executive tasks was smallest for the psychometric task considered to most heavily involve the central executive and largest for the task considered least demanding of executive mechanisms. We propose that, when applied to the assessment of central executive involvement, the prevalent simple dual-task logic does not always apply. Special conditions that limit the application of the dual-task methodology include two inherently related factors--a response selection bottleneck and a strategic tradeoff between primary and secondary tasks.     

Audio-visual integration of emotional cues in song

We examined whether facial expressions of performers influence the emotional connotations of sung materials, and whether attention is implicated in audio-visual integration of affective cues. In Experiment 1, participants judged the emotional valence of audio-visual presentations of sung intervals. Performances were edited such that auditory and visual information conveyed congruent or incongruent affective connotations. In the single-task condition, participants judged the emotional connotation of sung intervals. In the dual-task condition, participants judged the emotional connotation of intervals while performing a secondary task. Judgements were influenced by melodic cues and facial expressions and the effects were undiminished by the secondary task. Experiment 2 involved identical conditions but participants were instructed to base judgements on auditory information alone. Again, facial expressions influenced judgements and the effect was undiminished by the secondary task. The results suggest that visual aspects of music performance are automatically and preattentively registered and integrated with auditory cues.     

Attention and memory for threat in panic disorder

Recently, information processing paradigms have been utilized to explore the role of attentional and memory processes in the maintenance of clinical anxiety disorders. The present study extended these data using a dual-task paradigm to assess attentional vigilance and a cued recognition task to evaluate short-term memory effects in Panic Disorder (PD). Twenty PD patients and 20 normal controls completed a computerized task wherein they read aloud one of a pair of rapidly presented words (primary task) while simultaneously attempting to detect a small probe that appeared adjacent to one of the words (secondary task). Eighty stimulus words were chosen to represent four categories: physical panic-related threat, social threat, positive-emotional, and neutral. Reaction time and accuracy in detecting the probe were assessed, as well as psychophysiological responding (heart rate, skin conductance, EMG). Following task completion, a cued recognition task was administered to examine short-term memory of task stimuli. Results indicated that PD patients exhibited slower reaction times relative to normal controls during presentation of physical panic-related threat and positive-emotional stimuli. A similar trend emerged for social threat stimuli, although the PD and control samples responded similarly to neutral stimuli. No group differences were found on the cued recognition measure or psychophysiological responding during task performance. The data are discussed in terms of possible implications for cognitive models of PD.     

The role of input and output modality pairings in dual-task performance: evidence for content-dependent central interference

Recent debate regarding dual-task performance has focused on whether costs result from limitations in central capacity, and whether central operations can be performed in parallel. While these questions are controversial, the dominant models of dual-task performance share the assumption that central operations are generic--that is, their interactions are independent of stimulus and response modalities. To examine these issues, we conducted a series of dual-task experiments with different input and output modality pairings. One condition combined a visual-manual task with an auditory-vocal task, and the other condition reversed the input-output pairings, combining a visual-vocal task with an auditory-manual task. Input/output modality pairings proved to be a key factor; throughout practice, dual-task costs were generally more than twice as large with visual-vocal/auditory-manual tasks than with the opposite arrangement of modalities (Experiments 1 and 2). These differences could be explained neither by competition for peripheral resources nor by differences in single-task response times (Experiment 3). Moreover, the persistent dual-task costs did not appear to stem from a central bottleneck. Contrary to the dominant models of dual-task performance, we propose that central interference between tasks depends not just on the duration of central operations, nor just strategic adaptation, but also on the content of those operations. Implications for structural and strategic accounts of dual-task interference are discussed.